How Much Power, Part II

[PAULIE]

I would have guessed a 300 made well over 20 but it's not even close. The graphs show how differently trials-specific engines are tuned compared to their MX and Enduro cousins. And given these numbers, it seems crazy how 300's are often considered to be too much for the average rider. 

 

Edited January 22, 2023 by PAULIE

[greychapel]

Wow lookat the torque curve ln the gas gas, near vertical  from about 1500 to less than 2000 rpm. I've  found the gas gas 300 pretty rideable  actually, the 300 beta however i find tiring  to ride, be interesting  to see the figures  for it.

[PAULIE]

Indeed.

I searched for other modern trials bike dyno graphs but came up with nothing. 

[bikerpet]

I don't think power is so much the problem for "average riders" on a 300.
The problem is:
1. that near vertical torque curve off the bottom
2. the 6 or 8 kg of flywheel that just tractors on.

People get into grief when the bike accelerates away and then even if they cut the throttle it just keeps going on the flywheel - whiskey throttle but compounded by the fact that even if you chop the throttle the power on the tyre remains. The only way to cut the power is with the clutch.
The problem is really inadequate clutch control combined with the absolute tractor power of the 300's with their big flywheels.
It's interesting that one of the typical "solutions" for people wanting to tame a 300 is to put on flywheel weights. I guess that slows down the acceleration so the bike feels "tamer", but the downside must be that if it gets away without pulling clutch then it's going to be like a bulldozer - nothing's going to stop it!

If you compare a trials bike revving up to an enduro bike it's chalk and cheese - the trials bike takes several seconds to wind up and down (winding down from high revs takes ages - you usually drag clutch against brake to decelerate it quicker) because of the flywheel, while the enduros are way more on - off. That on-off characteristic means you can achieve much more effective control with throttle, that's just not an option on a 300 trials bike.

I don't think most people coming into trials really recognise just how big a factor the heavy flywheel on a trials bike is. So many moves are made with no throttle at all, just flywheel inertia, therefore HP is often almost completely irrelevant in those moves, it just means it takes a little longer to spin the flywheel up to speed. Of course there are also times you need sustained engine power, no doubt. Look at the really good 125cc riders, it's incredible what they can send those things up with a fraction of the power of a 300, they just store power in the flywheel for when they need it. Flywheel energy goes up by the square of RPM, so a relatively light 125 flywheel can still store a heap of energy as they tend to rev a bit faster.

My 2c

[UG_ALLSTAR]

The TXT torque looks like a dyno line from a forced induction motor.